1. Field of the Invention
The present invention relates to generally to inspection of irregularity or unsteadiness possibly appearing on the surface of objects, specimens and the like, and more specifically to a method and apparatus for detecting surface irregularity of objects, e.g., less conspicuous spots with imperceptible boundary scattered on an object surface, blot zones of differing density often present on the patternless homogeneous surface of a monolithic object, flaws on a patternless sheet-like specimen, and positional defects in an array of objects arranged at a predetermined pitch. Even more particularly, the instant invention is directed to a method and apparatus capable of examining stains or stain areas, minute flaws and crosswise defects of unclear boundary with no remarkable brightness difference, frequently appearing on the surface of various articles.